Year	Percent
1999	1.78
2000	2.13
2001	2.15
2002	2.56
2006	3.11
2007	3.36
2008	2.84
2009	3.39
2011	3.92
2012	3.85
2013	3.87
2014	4.04
2015	4.23
2016	4.53
2018	4.78
2020	6.14